Geopolymer additives and methods of use for treatment of fluid fine tailings

1. A method for forming an oil sand fine tailings deposit having a minimum undrained shear strength of 5 kilopascals at about one year following depositing, the method comprising:

flowing a stream of fluid fine tailings having a solid content of about 25 wt % to about 55 wt %;

adding and mixing an effective amount of a dry geopolymer to the stream of fluid fine tailings for forming a geopolymer-treated tailings stream; comprising geopolymer from about 0.2 wt % to about 3 wt % of the dry solids content of the fluid fine tailings stream;

adding an effective amount of one or more rheology modifiers to the stream of fluid fine tailings for temporarily postponing reaction between the geopolymer and the fluid fine tailings for enhancing dewatering of the fluid fine tailings until the solids content is about 60 wt % or greater;

imparting shear to the geopolymer-treated tailings stream during the adding and mixing step; and

depositing the geopolymer-treated tailings stream for forming the deposit, the deposit being exposed to ambient weather conditions,

wherein the dry geopolymer is one or more of Class C flyash, activated Class F flyash, cement kiln dust (CKD), activated Landfill cement kiln dust (LCKD), activated colloidal silica, microwave incinerated rice husk ash and ground granulated blast furnace sludge.

2. The method of claim 1 further comprising:

feeding the dry geopolymer from a hopper to the flowing stream of fluid fine tailings; and

imparting the shear to the geopolymer-treated tailings stream using one or more in-line mixers.

3. The method of claim 1 further comprising:

adjusting the pH of the fluid fine tailings stream before the addition of the geopolymer, after the addition of the geopolymer or both for controlling quality of water released from the deposit.

4. The method of claim 1 further comprising:

depositing the geopolymer-treated tailings stream at a dedicated disposal area.

5. The method of claim 4 further comprising:

depositing the geopolymer-treated tailings stream in a plurality of thin lifts or a plurality of thick lifts.

6. The method of claim 5 further comprising:

depositing each of the lifts at a time interval of about one to about two weeks from a previously deposited lift.

7. The method of claim 5 further comprising:

depositing the geopolymer-treated tailings stream at the dedicated disposal area in multi-layer thin lifts, each of the thin lifts of the multi-layer thin lifts being about 25 cm±10 cm and resulting in up to about 3.5 m±0.5 m total height per year.

8. The method of claim 5 further comprising:

depositing the geopolymer-treated tailings stream at the dedicated disposal area in multi-layer thick lifts, each of the thick lifts of the multi-layer thin lifts being about 1 meter and resulting in up to about 4 m±1 m total height per year.

9. The method of claim 7 wherein being exposed to ambient weather conditions further comprises:

exposing each of the thin lifts to natural drying.

10. The method of claim 8 wherein being exposed to ambient weather conditions further comprises:

exposing each of the thick lifts to one or more freeze and thaw cycles.

11. The method of claim 1 wherein the activated geopolymer is not self-activating, prior to adding the geopolymer, the method further comprising:

adding an effective amount of an activator to activate the geopolymer.

12. A system for practicing the method of claim 1 wherein the dry geopolymer is added to the flowing stream of fluid fine tailings, comprising:

one or more high shear, in-line mixers for mixing the dry geopolymer material with the stream of fluid fine tailings and imparting the shear thereto.

13. A geopolymer-treated fluid fine tailings mixture, adapted for depositing and forming a deposit having a minimum undrained shear strength of 5 kilopascals one year following depositing, comprising:

a stream of fluid fine tailings having a solid content of about 25 wt % to about 55 wt %; and

an effective amount of a dry geopolymer comprising one or more of Class C flyash, activated Class F flyash, cement kiln dust (CKD), activated Landfill cement kiln dust (LCKD), activated colloidal silica, microwave incinerated rice husk ash and ground granulated blast furnace sludge; and

a rheology modifier for temporarily postponing reaction between the geopolymer and the fluid fine tailings for enhancing dewatering of the fluid fine tailings until the solid content is about 60 wt % or greater,

wherein an amount of the dry geopolymer added is from about 0.2 wt % to about 3 wt % of the dry solids content of the fluid fine tailings stream; and

wherein shear is imparted to the mixture during addition of the geopolymer to the stream of fluid fine tailings.

14. The geopolymer-treated fine tailings mixture of claim 13 wherein the pH is adjusted prior to addition of geopolymer, after the addition of geopolymer or both, for controlling quality of water released from the mixture.

15. The geopolymer-treated fine tailings mixture of claim 13 wherein the dry geopolymer is not self-activating, the mixture further comprising:

an activator to activate the geopolymer.

16. A geopolymer-treated fluid fine tailings mixture, adapted for depositing and forming a deposit having a minimum undrained shear strength of 5 kilopascals one year following depositing, comprising:

a stream of fluid fine tailings having a solid content of about 25 wt % to about 55 wt %;

a dry geopolymer comprising one or more of Class C flyash, activated Class F flyash, cement kiln dust (CKD), activated Landfill cement kiln dust (LCKD), activated colloidal silica, microwave incinerated rice husk ash, ground granulated blast furnace sludge; and

a rheology modifier for temporarily postponing reaction between the geopolymer and the fluid fine tailings for enhancing dewatering of the fluid fine tailings until the solid content is about 60 wt % or greater,

wherein the geopolymer is added in an amount greater than about 0.2 wt % of the dry solids content of the fluid fine tailings stream; and

wherein shear is imparted to the mixture during addition of the geopolymer to the stream of fluid fine tailings.

17. The geopolymer-treated fine tailings mixture of claim 16 wherein the dry geopolymer is not self-activating, the mixture further comprising:

an activator to activate the geopolymer.